As a technique for optically connecting a multicore fiber and a single-mode fiber, a scheme for using a lens system in which a plurality of lenses are arranged between the fibers and a scheme for using a connector are known. For example, International Publication WO2014/038514 (Patent Literature 1) describes an optical connector that has a first lens which an emission light from a plurality of cores included in a multicore fiber enters, a second lens which the emission light from the first lens enters, and a lens array which the emission light from the second lens enters, wherein the emission light from constituent lenses included in the lens array enters corresponding single-mode fibers, and thus the multicore fiber and the single-mode fibers are optically connected. Further, “Development of Multicore Fiber and Fan-in/Fan-out Device” by Masatoshi Tanaka, Masayoshi Hachiwaka, and Hirokazu Taniguchi; Mitsubishi cable Industries, Ltd. R&D Review, No. 109, September 2012 (Non-Patent Literature 1), and “Connector-type Fan-Out Devices for Multi-Core Fiber” by Osamu Shimakawa, Hajime Arao, Manabu Shiozaki, Tomomi Sano and Akira Inoue, SEI Technical Review, No. 183, July 2013 (Non-Patent Literature 2) describe fan-out function components that separate the multicore fiber pin provided with a plurality of cores at a center into a plurality of single-core fibers.